In a cellular mobile communication system shown in FIG. 1, communication links at radio side include uplinks and downlinks. Through the downlinks, a base station may send data to terminal devices, and through the uplinks, the terminal devices may send data to the base station. Taking a Long Term Evolution (LTE) system as an example, the communication between a terminal device and a device at network side is illustrated hereinafter, and the state detection of radio links between the terminal device and the device at the network side is also illustrated hereinafter.
In the LTE system, when the terminal device initiates a service, the terminal device establishes a connection with the device at the network side firstly. Afterwards, the terminal device sends uplink data on uplink radio resources, and receives downlink data on downlink radio resources. The uplink radio resources and the downlink radio resources are both assigned by the device at the network side. When the terminal device terminates the service, the device at the network side releases the connection established by the terminal device, and reclaims the resources that are previously assigned and used during the communication.
When the terminal device moves or the communication environment changes, the quality of communication links between the terminal device and the device at the network side changes. In order to ensure the acceptable communication of the terminal device, the quality of signals received and sent by the terminal device should be higher than a threshold. Accordingly, in the LTE system a common pilot signal is configured, which is used to detect the quality of downlink signals in real time by the terminal device.
A process of detecting a radio link by the terminal device is as follows. Through constants N310 and N311 as well as a timer T310, the terminal device detects whether the radio link is failed. When the terminal device is in a connection state, the physical layer of the terminal device continuously detects the quality of downlink channel of serving cell. When determining that the quality of downlink channel is lower than a threshold, the physical layer of the terminal device sends an “out-of-sync” instruction to a high layer of the terminal device. When determining that the quality of downlink channel is higher than the threshold, the physical layer of the terminal device sends an “in-sync” instruction to the high layer of the terminal device.
As shown in FIG. 2, when receiving N310 continuous “out-of-sync” instructions, the high layer of the terminal device determines that the radio link is failed temporarily, and starts the timer T310. T310 specifies a maximum time of waiting for the restoration of the radio link. When the high layer of the terminal device receives N311 continuous “in-sync” instructions and the timer T310 has been started, the high layer of the terminal device determines that the radio link has been restored, and stops the timer T310. If the timer T310 expires, it is indicated that the radio link has been failed, and the terminal device initiates a connection reestablishment process to restore the radio link. If the radio link has not been restored, the terminal device enters the idle state.
It should be noted that, when the physical layer of the terminal device determines that the signal quality of the radio link is lower than the threshold and sends the “out-of-sync” instruction to the high layer of the terminal device, the terminal device has been unable to receive or send data normally. At this time, if the device at the network side still assigns uplink or downlink resources to the terminal device, these resources may be wasted.
Accordingly, the device at the network side needs to detect the signal quality of radio link of the terminal device. When determining that the signal quality of radio link of the terminal device is lower than the threshold, the device at the network side does not schedule the terminal device any more before the signal quality of radio link is restored. At present, the terminal device is usually configured with periodical uplink resources, and the signal quality of the periodical uplink resources is detected to determine whether the radio link of the terminal device is normal.
The inventor finds following problems in the prior art.
In the prior art, the device at the network side configures the periodical uplink resources and detects the signal quality of the periodical uplink resources to determine whether the radio link of the terminal device is failed. However, in an actual system, it is because of the limit of available resources that the periodical uplink resources may not be configured to each terminal device being in the connection state. Or, even if the periodical uplink resources are configured to each terminal device being in the connection state, the periodical uplink resources configured to a certain terminal device may be released if the terminal device has not received and sent data for a long time and thus enters an uplink desynchronization state. As can be seen, a method for effectively detecting the signal quality of radio link of the terminal device has not been provided in the prior art.